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createHash.js
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Mon, Feb 10, 11:17

createHash.js
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/*
MIT License http://www.opensource.org/licenses/mit-license.php
Author Tobias Koppers @sokra
*/
"use strict";
const Hash = require("./Hash");
const BULK_SIZE = 1000;
const digestCache = new Map();
class BulkUpdateDecorator extends Hash {
/**
* @param {Hash | function(): Hash} hashOrFactory function to create a hash
* @param {string=} hashKey key for caching
*/
constructor(hashOrFactory, hashKey) {
super();
this.hashKey = hashKey;
if (typeof hashOrFactory === "function") {
this.hashFactory = hashOrFactory;
this.hash = undefined;
} else {
this.hashFactory = undefined;
this.hash = hashOrFactory;
}
this.buffer = "";
}
/**
* Update hash {@link https://nodejs.org/api/crypto.html#crypto_hash_update_data_inputencoding}
* @param {string|Buffer} data data
* @param {string=} inputEncoding data encoding
* @returns {this} updated hash
*/
update(data, inputEncoding) {
if (
inputEncoding !== undefined ||
typeof data !== "string" ||
data.length > BULK_SIZE
) {
if (this.hash === undefined) this.hash = this.hashFactory();
if (this.buffer.length > 0) {
this.hash.update(this.buffer);
this.buffer = "";
}
this.hash.update(data, inputEncoding);
} else {
this.buffer += data;
if (this.buffer.length > BULK_SIZE) {
if (this.hash === undefined) this.hash = this.hashFactory();
this.hash.update(this.buffer);
this.buffer = "";
}
}
return this;
}
/**
* Calculates the digest {@link https://nodejs.org/api/crypto.html#crypto_hash_digest_encoding}
* @param {string=} encoding encoding of the return value
* @returns {string|Buffer} digest
*/
digest(encoding) {
let cacheKey;
if (this.hash === undefined) {
// short data for hash, we can use caching
cacheKey = `${this.hashKey}-${encoding}-${this.buffer}`;
const cacheEntry = digestCache.get(cacheKey);
if (cacheEntry !== undefined) return cacheEntry;
this.hash = this.hashFactory();
}
if (this.buffer.length > 0) {
this.hash.update(this.buffer);
}
const digestResult = this.hash.digest(encoding);
const result =
typeof digestResult === "string" ? digestResult : digestResult.toString();
if (cacheKey !== undefined) {
digestCache.set(cacheKey, result);
}
return result;
}
}
/* istanbul ignore next */
class DebugHash extends Hash {
constructor() {
super();
this.string = "";
}
/**
* Update hash {@link https://nodejs.org/api/crypto.html#crypto_hash_update_data_inputencoding}
* @param {string|Buffer} data data
* @param {string=} inputEncoding data encoding
* @returns {this} updated hash
*/
update(data, inputEncoding) {
if (typeof data !== "string") data = data.toString("utf-8");
if (data.startsWith("debug-digest-")) {
data = Buffer.from(data.slice("debug-digest-".length), "hex").toString();
}
this.string += `[${data}](${new Error().stack.split("\n", 3)[2]})\n`;
return this;
}
/**
* Calculates the digest {@link https://nodejs.org/api/crypto.html#crypto_hash_digest_encoding}
* @param {string=} encoding encoding of the return value
* @returns {string|Buffer} digest
*/
digest(encoding) {
return "debug-digest-" + Buffer.from(this.string).toString("hex");
}
}
let crypto = undefined;
/**
* Creates a hash by name or function
* @param {string | typeof Hash} algorithm the algorithm name or a constructor creating a hash
* @returns {Hash} the hash
*/
module.exports = algorithm => {
if (typeof algorithm === "function") {
return new BulkUpdateDecorator(() => new algorithm());
}
switch (algorithm) {
// TODO add non-cryptographic algorithm here
case "debug":
return new DebugHash();
default:
if (crypto === undefined) crypto = require("crypto");
return new BulkUpdateDecorator(
() => crypto.createHash(algorithm),
algorithm
);
}
};

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